When a photo appeared on my aeroplane appeared on G-INFO, I contacted the CAA.
Despite official mutterings about Privacy

they did send me contact details. I can't remember how they did this, but I know they did, despite being seemingly unaware of the irony regarding
our privacy.
So that's one answer, assuming you've Googled your registration and the photo didn't come up on a spotter's site, which would be my first search.